Ultra-Large-Scale Continuous-Variable Cluster States Multiplexed in the Time Domain

Abstract: Quantum computers promise ultrafast performance of certain tasks. Experimentally appealing, measurement-based quantum computation (MBQC) requires an entangled resource called a cluster state, with long computations requiring large cluster states. Previously, the largest cluster state consisted of 8 photonic qubits or light modes, while the largest multipartite entangled state of any sort involved 14 trapped ions. These implementations involve quantum entities separated in space, and in general, each experimental apparatus is used only once. Here, we circumvent this inherent inefficiency by multiplexing light modes in the time domain. We deterministically generate and fully characterise a continuous-variable cluster state containing more than 10,000 entangled modes. This is, by 3 orders of magnitude, the largest entangled state ever created to date. The entangled modes are individually addressable wavepackets of light in two beams. Furthermore, we present an efficient scheme for MBQC on this cluster state based on sequential applications of quantum teleportation.